Breather roof



April 21, 1942. L. A. wlLKlN ET AL BREATHER ROOF Filed sept. 1s, 1959 2 Sheets-Sheet 1 Z/ u A Huef SWW M,

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April 21, 1942- L. A. wxLKlN ETAL I 2,280,679

BREATHER ROOF Filed Sept. 18, 1939 2 Sheets-Sheet 2 fi( 53 2Q M l QZ Q3 QQ f 5 --lf- 164.2 32/ i z 1 I o. i l

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Patented pr. 2l, 1942 BREATHER ROOF Lester A. Wilkin and Hubert Smith, East Chicago, Ind., assig'nors to Graver Tank & Mfg. Co., Inc., Catasauqua, Pa., a corporation of Delaware Application Septemberv 18, 1939, Serial No. 295,378

(Cl. IS-176) 2 Claims.

The yinvention relates to storage tanks i'or storing gases or volatile liquids and has reference more particularly to an improved gas holder type of roof for said tanks capable of moving bodily in a vertical direction to vary the volume of vapor space within the tank.

Tanks of the type above described are fairly large in diameter and therefore the surface area of liquid subjected to variable vtemperature conditions is substantial. Accordingly, during the heat of the day the vapors produced as a result of evaporation will materially increase the pressure within the tank. However, if these vapors are conserved they can be reclaimed during the night, owing to the cooler night temperature, which condenses the vapors. The production of vapors during the day followed by subsequent cooling and condensing of the vapors during the night is known as breathing, and in large tanks, particularly if only partly i'llled, such breathing will be substantial. Also when the oil is pumped into such tanks the agitation increases the generation of vapors. However, filling of the tank with oil decreases the vapor space and here also the vapor pressure within the tank may become dangerously high.

It is well known that severe evaporation losses will result during the storing of volatile liquids such as gasoline and the like if the vapors are expelled to the atmosphere in order to relieve the pressure within the tanks. Thus, as a matter of economy, it is necessary to conserve said vapors so that they can be eventually condensed without any loss of the valuable fractions.

The invention has for its primary object to provide an improved gas holder type of roof for oil storage tanks which as a result of its movement will provide ample vapor space to take care of breathing of the tank under any and all conditions.

Another and more specific object is to provide a roof of the type described whichA will have considerable movement in a vertical direction to vary the vapor space within the tank so that it will not be necessary to discharge any vapors to the atmosphere even under severe breathing conditions. l

A further object of the invention is to provide a gas holder type of roof with improved means for maintaining the roof substantially horizontal during movement thereof in an upward and downward direction and which will also prevent undesirable rotation of the roof with respect to the tank.

A further object of the invention is to provide improved means for controlling the movement of a gas holder type of roof so that the same may rise and fall in a true vertical direction and which will additionally strengthen and reinforce the roof whereby the samemay withstand a greater pressure than would otherwise be the case.

With these and various other objects in view, the invention may consist of certain novel features of construction and operation as will be more fully described and particularly pointed out in the specification, drawings and claims appended hereto.

In the drawings which illustrate an embodiment of the invention and wherein like reference characters are used to designate like parts- Figure 1 is a view illustrating one embodiment of the invention with the upper portion of the tank and roof being shown in section and with the roof in deflated position;

Figure 2 is a fragmentary sectional view of the tank of Figure 1 showing the roof in inflated position; and

Figure 3 is a fragmentary sectional view illustrating a modification coming within the invention.

The embodiment of the invention shown in the drawings comprises an open toptank having cylindrical side walls I0, a base Il adapted to rest on the earth or other suitable support, and supporting structure including rafters l2 and vertical posts I3. The supporting structure is designed to support the roof in deflated position and to transmit the weight of the roof directly to the side wall and base of the tank. The rafters l2 have connection with the side wall of the tank by means of a shell girder M, which is suitably secured as by welding and by the angle member l5 to the tank wall at the extreme upper end thereof. The shell girder stiffens the upper end of the tank and is in turn reinforced by the member I6 of angle shape in cross section. having its horizontal leg directed inwardly. The shell girder and member I6 extend around the inside periphery of the tank wall and are suitably supported at intervals from said wall by the plate brackets I8.

The structure above described provides supporting means particularly adapted for supporting the outer ends of the rafters I2 which are radially disposed with respect to the center posts I3. Said rafters sustain the roof ZIJV of the tank when in deflated position and accordingly said rafters substantially conform to the shape of the roof, whereby the stresses are evenly distributed and the roof is thus able to rise from the structure freely and easib` upon a relatively low vapor pressure existing within the tank.

The outer circumference of the tank at the upper end is provided with a launder 2| formed by the cylindrical member 22 which is spaced from and concentric with the wall I of the tank. The launder is completed by the member 23 which forms the base of the same and the bottom of the trough which is adapted to contain oil or other sealing liquid.

The roof for the open top tank is in the form of a holder bell having telescoping relation with respect to the cylindrical wall I0. The bell includes a cambered roof 24 having a depending skirt 25 for location within the launder and also having a depending rain shed skirt 25 which forms a cover for the launder, protecting the same and its associated equipment from the weather. The rain shed skirt is concentric with skirt 25 and the same is suitably secured to the outer periphery of the roof 24 as by the angle member 21. The lower end of skirt 25 is guided during vertical movement of the holder bell by means of rollers 28 and 30. As better shown in Figure 2, the rollers are journalled by brackets 3| and iixed to the skirt by said brackets. The rollers extend in opposed directions and thus contact the side wall I0 of the tank and also the interior of the cylindrical member 22. Although only two pair of rollers are shown in Figure l, it is understood that any number may be used. depending on the size of the tank, and that the same will be spaced around the skirt 25, being secured preferably to its lower end.

In accordance with the invention. the holder bell is additionally guided by rollers 32, having contact with guide rails 33 fixed to the side wall I0 of the tank. Brackets 34 journal the rollers 32, respectively, and said brackets are in turn carried by guide channels 35, which depend from the holder bell and are suitably secured to the rain shed skirt 26 and to the roof 24. Plates 35 o1' substantially triangular shape complete the latter connection and said plates in addition considerably strengthen and stifien the outer periphery of the roof.

The holder bell in moving up and down to increase or decrease the vapor space within the tank is accordingly guided so that its movement takes place in a vertical direction and the roof is also maintained substantially horizontal. The rollers 32 ride on the guide rails 33. The rollers in the launder directly contact their respective cylindrical member. However, pressure exerted by a roller is resisted by a roller 31 carried by a guide channel 35 and for the roller 23 the wall l0 of the tank is stiiened along its path of A movement by the shell stitener 35 placed opposite the same.

In the modification of the invention shown in Figure 3 the open top tank having a cylindrical side wall and a base (not shown) is likewise provided with supporting structure including radially disposed rafters 42 which are supported at their outer ends by an angle member 43 forming part of the shell girder structure 44 and which extends around the interior of the tank wall at the upper end thereof. The roof 45, of the bell holder type, has a depending skirt 45 and a rain shed skirt 41. The former has location within a launder formed by the outer cylindrical member 48, and the rain shed skirt has suitably secured thereto the depending guide channels joining with the roof by means of the plate brackets 5I and carrying at their lower end brackets 52 journalling the rollers 53.

In this form of the invention the rollers 53, carried by the guide channels, may have contact directly with the cylindrical wall Il of the tank. In other words. the guide rails employed for these rollers in Figure l are omitted in this modiiication and instead said guides are located within the launder in order to guide the depending skirt 45 of the holder bell. The guide rails 54 are spaced so as to allow passage therebetween of the single roller 55 iixed to the lower end of the skirt 45. The rails, since they are located within the launder, also function to stillen the upper portion of the tank side wall and the outer cylindrical member 48. However, outward pressure of roller 55 is resisted by the roller 55 carried by the channel guide 50.

In the operation of the storage tank forming the subject matter of the present invention the launder is filled with a sealing liquid such as water or oil and the space within the tank may also contain oil such as gasoline or kerosene' or the tank may be used as a gas reservoir. In either case, the pressure within the tank may at times exceed the weight of the holder bell and thereby cause the same to rise in order to increase the vapor space and relieve the high pressure. A roof ofthe kind described may have considerable movement and accordingly the space thus provided will be ample to take care of breathing of oil storage tanks under the most severe conditions. The roof of the invention can be easily adapted to old tanks and can of course be employed with new tanks. It is oi' prime importance that the roof move up and down in a true vertical plane and this is the function of the guide channels and the rollers carried by the same and by the depending skirt of the holder bell. The additional stiiening and reinforcing of the holder bell which results by reason of the guide channels is also desirable since the stresses are more evenly distributed throughout the roof, and the holder bell, particularly when inflated, is better able to withstand a high wind and to maintain its freedom of movement while also maintaining its substantially horizontal position.

What is claimed is:

l. In a storage container for petroleum products and the like, in combination, an open top tank having a launder at the open end thereof containing sealing liquid, a movable root for said open top tank including a holder bell having its depending skirt located within the sealing liquid so as to confine vapors within the tank, a rain shed skirt depending from the vperiphery of said movable roof and encircling the launder to provide protection therefor against the elements, means guiding the holder bell during movement thereof to increase or decrease the vapor space within the tank including rollers fixed to the lower end of the depending skirt and having contact with the side walls of the launder, members fixed to the rain shed skirt and depending below the launder, rollers carried by the depending ends of said members respectively, and guide rails fixed to the cylindrical wall of the tank with which said rollers are adapted to engage whereby movement of the holder bell in a vertical direction is additionally guided andl whereby the roof is maintained substantially horizontal during said movement.

2. In a storage container for petroleum products and the like, in combination, an open top tank having a launder at the open end thereof containing sealing liquid, a movable rooitor said open top tank including a holder bell having its depending skirt located within the sealing liquid so as to conne vapors within the tank. a rain shed skirt depending from the periphery of said movable roof and encircling the launder to provide protection therefor against the elements.v

means guiding the holder bell during movement thereof to increase or decrease the vapor space within the tank including rollers xed to the lower end of the depending skirt and having contact with the side walls of the launder, members xed to the rain shed skirt and depending below LETER A. WILKIN. HUBERT SMITH. 

